Paraffin cutter and scraper



INVENTOR @Wiz/May ATTORN J. F. MCKAIG PARAFFI-N CUTTER AND SCRAPER Filed Sept. 6. 1957 Www,

May 17, 1960 United States Patent PARAFFIN CUTTER AND SCRAPER Jesse F. McKag, Crescent, Okla.

Application September 6, 1957, Serial No. 682,462 Y 2 Claims. (Cl. 166-173) This invention relates to apparatus for removing the layer of parain or other deposits which progressively builds up on the inside wallA of the tubing or casing of oil wells. Y n Y One of the objects of the present inventionis to provide apparatus of the character described, in which a relatively short annular cutting cylinder that slidably tits the tubing within which it functions, is reciprocably mounted upon a suspended member operated from the top of the well, thevweight of which suspended member plus the weight of the suspending string, forces the cutting cylinder down through the parain, there being a passage between the cylinder and suspended member throu-gh which the debris detached by the cylider is extruded upward as the apparatus is lowered, to ll the tubing'above apparatus vwith suiiicient material to constitute a load, which is withdrawn from the well by pulling the'apparatus up to the surface.

Another object of the invention is the provision of apparatus as described, in which the lower end of the suspended member serves as a valve to close the passage between itself and the cutting cylinder. when drawn up into engagement with lthe latter, to prevent the debris from spilling back into the tubing -as the `apparatus is withdrawn. I

A further object of the invention is thelprovision of apparatus Ias described, in which the suspended member is furnished with stops above the cutting cylinden'determining lower limit of the range of reciprocatory movement of the suspended member, which may be brought down impactively against the cylinder as repeatedly as necessary with all the weight of the apparatus and the suspending means, for driving the cutting cylinder through particularly tough and resistant material.' f

Still another object of the invention is the use'of the apparatus herein described, as a pumpin conjunction with the checkfvalve at the foot of the producing pipe, for lifting the column of oil which extends above said check valve. Y

Other objects of the invention will appear as the following description of a practical embodiment thereof proceeds.

In the drawing which accompanies Aand forms a part of the following specification:

Figure 1 is a longitudinal axial section through a portion of the well tubing showing the paraflin cutting apparatus partly in section `and partly -in elevation, the suspended member being in elevated position with respect l Patented Mey 17, 4,19.6.0

Figure 4 is a cross section taken along line 4-4 of' The suspended member 2 1s preferably made of steel,

of round stock having arsmaller diameter than the tubing or casing within wh-ich it is designed to operate, and

" beingthreaded at both ends, the upper end -4 iitting whatever suspending means are employed.

The drawing is 4made from apparatus designed for two` inch tubing and the upper end is threaded to couple to standard sucker rod. The lower end 5 is similarly threaded to receive a sucker rod coupling 6, for attach-l ment of a section -ofv sucker rod or a string of more than Aone section, for supplying needed weight to cause the apparatus to more easily go down the hole. This cou` pling 6 or its equivalent is an essential part of the suspended component of the para'in removing apparatus to the extent that it provides the annular shoulder 14 which the lower end of the cutting cylinder 3 cooperates to form a valve, as will appear. It is to be understood that the device can be manufactured in various sizes for all sizes of tubing and casing. used in casing, sections of tubing would be used instead of sucker rods and the coupling 6 would be a tubing coupling.

Immediately below the threaded end 4 of the suspended member, there is a square section 7 sized to tit aV standard wrench for attaching the `apparatus to` the suspending string and also holding it while tightening the connec' tion-at the opposite end. Between the wrench hold sec.

tion .7 and the lower end, the suspended member is i formed with a body 15 which has an end face 16 of circular periphery surrounding the wrench hold sectionvr7. Between its ends the body 15 is indented to form three longitudinal vanes 8 which extend radially at 120 displacement from Ia Vcommon axial web 9, said vanes defining between them longitudinal passages which are open in the later-al surface of the body. The vanes are of different radial dimensions in dilferent zones. InV an intermediate zone they are formed with longitudinal extensions 9 which approach close to the wall of the well tubing 'and' guide the suspended member therein. In the `lower zone the edge faces of the vanes are in guiding relation to the cutting cylinder 3, while -in the upper zone the vanes are spaced an appreciable distance from the inner wall of the tubing to provide a full circumferential discharge passage for the parain debris yand the vehicle oil |which carries it upward. I

The specic cross-sectional shape of the vanes is not material to the invention. As shown, their portions re mote from the axis of the web 9 have parallel sides and are of suflicient thickness to minimize wear of their outer faces or of the surfaces against which they rub. Adjacent the web the faces of adjacent ribs are routed out to form indentations 19 of circular curvature, the purpose being to increase the cross-sectional area ofthe tlow passages.

If it is to be- Neartheir ends the sidesv of the vanes slopetoward one another, merging to form streamline surfaces against which the oil and parafin debris flow without turbulence and without being obstructed. The effect of the spreading of the side walls of the vanes is to widen their outer faces adjacent their ends. Since the varies, -as shown, terminate some distance from the lower end of the body 15, the portion 17 of the body below the vanes is of continuous cylindrical curvaturei The lower ends 18 of the extensions 9 function as stops, being engageable with the adjacent end of the cylinder 3.

The cutting cylinder is sized to. slidably fit the tubing o -r casing in which it -is tobe used. It is of annular construction surrounding the vanes S below the extensions 9', being guided by the vanes and making a neat sliding tit-with the outer edges of the vanes, which are beveled complementary to the curvature of the inner wall of the cutting cylinder. The latter is provided at its lower end with an inward circumferential chamfered face 10, forming a peripheral knife edge 11 about its outer wall. The cutting cylinder is also formed at its upper end with an inwardly beveled face 12, which defines a less acute peripheral scraping edge 13 at its outer wall. The adjacent ends 18 of the extensions 9 are beveled to correspond to the slope of the face 12.

The suspended member 2 and cutting cylinder 3 are relatively reciprocable through a range limited at one endby the Contact of the lower ends 18 of the extensions 9 with the upper' end of the cylinder and at the other end bycontact of the cylinder with the coupling 6, which contacts the chamfered face inwardly of the knife edge, said coupling functioning as a valve to Seal the lower end of the cylinder as the apparatus is withdrawn.

As the tool is lowered down the bore of the tubing or casing, as the case may be, the lower cutting edge cuts or shaves oif the paraiiin, which is extruded through the passages between the Vanes, the cylinder being forced downward by the weight of the suspending string plus the weight of such additional rod or pipe sections as it may have been thought desirable to attach to the lower end of the suspended member. When the tool has been lowered a considerable distance down the hole, and the operator feels that he has a suiiicient load of paraiiin on' top of the scraper, he reverses the procedure and starts to withdraw the coupling string from the hole. As the tool is raised, the coupling 6 movesV up into sealing relation to the chamfered face 10 of thecylinder and prevents any part of the load of debris from slipping back into the well. As the device ascends the bore of the tubing, the upper less acute peripheral edge of the cutting cylinder scrapes against the side of the tubing, and cleans oiff'any loosened paraffin that may have beenV left by the tool on its way down.

One of the outstanding features which contributes to the operative eiiiciency of this tool is the jarring action that can be produced by raising the suspended memberto establish the desiredV distance between the stops 18 a distance from the upper end of the cylinder, then letting the suspended member fall, bringing the stops into impactive engagement with the cutting cylinder, with all the weight of the suspending string, and the weight of the added sections at its lower end, concentrated in the blow. This may be counted upon to maintain the cutting action of the cylinder 3 in places of the toughest character, even when outcroppings of corrosive scale are encountered.

It is to be understood that this apparatus will work on salt, sulphur or asphalt deposits in tubing or casing, as well as it does on paraiiin. It also works quite well in oil wells which are flowing, and therefore, do not have pumping rods or pipe strings available for operating the tool. In such case, a wire line is employed for suspending the apparatus. After a sufficient weight has been tied to the lower end of the tool to compensate for the absence of the weight of a suspending string. v The only adjuncts required would be lcouplings screwed to the opposite ends of the suspended member provided with eyes for the attachment, on the one hand, of the suspending wire, and on the other, the bottom weight. For convenience, the bottom weight may be minimized, and its lightness compensated by more continual use of the impact or jarring mode 0f operation as already described in the case of a flowing well. The oil and gas, entering passages between the varies eachV time the lower coupling moves away from the lower ""end of the cylinder on the down stroke, carry the deposits which have been cut off, upward and finally to the surface, so that it becomes unnecessary to withdraw the apparatus and its load of debris from time to time during the cleaning operation.

The apparatus Vof the present invention may kfunction as a pump, particularly in tiowing wells. Since the descent of the cylinderralways lags relative to kthe descent of the actuator, the passage through the apparatus is open throughout the downward stroke of the suspending means. Upon the beginning of the upstroke of the suspending means, the lower end of the cylinder is closed so that the speed of ascent of the apparatus exceeds that of the natural iiow, the entire column of liquid above the valve being lifted. Y

It is essential, of course=that the cylinder 3 be a reasonably close sliding t with the wall of the tubing string, and the fact that it is guided by the varies 8 keeps it coaxial with the tubing and prevents its edges from unequally wea-ring into the wall of the tubing or becoming themselves unequally worn. The dual functions of parafiin scraper and pump can be concurrently performed in wells Vthat have the parain or other coating on the walls of the tubing.

It will be obvious to one skilled in the art that the structure of the subject paraflin cutter and scraper, as well as its mode of operation, areextremely simple, the tool consisting essentially of only two parts, the suspended member and the cutting cylinder, since the coupling at the lower end is a standard sucker rod or tubing coupling, generally to befoundvat the well where the parain removal service -is to be performed. It is envisioned that due to its sturdiness and simplicity, the tool will last for many years with only the cutting cylinder needing to be replaced,u at long intervals.

While I have in Ythe above description disclosed a practical embodiment of theinventiom itwill Vbe understood not to beconstrued as limiting the scope of the invention. What I claim is:V

l. Parafiin remover for oil w`ells and the like cornprising yan annular open ended'cutting cylinder having a-circumferential knife edge at, its'lower end, and an actuator therefor upon which said cylinder is retained, freely `reciprocable relative thereto, said actuator being adapted `to be reciprocably suspended in a'well tubing, said actuator comprising an elongate cylindrical body formed with a circumferential series of longitudinal channels terminating short of the lower end of said body, defining between them longitudinal circumferentially displaced vanes having portions of different radial dimensions in different zones, their edges faces slidably fitting the bore of said cylinder in a lower zone, and slidably tting the bore of the well tubing in a contiguous upper zone, the Vlower ends of the portions of said vanes in said upper zone forming shoulders adapted to engage the upper end of said cylinder upon the downward stroke of the suspending means, and the relative lengths of said channels and cylinder beingA such that when said shoulders arein engagement with said cylinder, the lower ends of said channels extend below said cylinder in communication with the well tubing, the lower end of said body below said vanes being 4cylindrical and slidably fitting the bore of said cylinder, the lower end of said body beingprovided-with retaining means engageable by the lower portion of said cylinder cooperating with said shoulders' to determine the range of relative movement between said cylinder and actuator. c

2. Parain remover for oil wells andthe like as claimed in claim 1, said retaining means at the lower end of said body being inthe form of an outwardly extending peripheral shoulder forming a circumferential valve seat for the lower end of said cylinder cooperating therewith to form a valve closure when engaged by the lower end of said cylinder upon the upstroke of said actuator.

References Cited in the le of this patent UNITED STATES PATENTS Gaskill Ian. 1l, 1881 Miller July 9, 1929 Penrod Dec. 12, 1939 Irwin Aug. 7, 1951 Irwin Julyf 12, 1955 j Bryant Nov. 18, 1958 

